Deciding on breast cancer treatments is a balancing act -- you want to choose the ones that are most effective AND have the fewest side effects. A small study of 54 women may give doctors another tool to measure how effective chemotherapy is against metastatic breast cancer.

Using a simple test, researchers measured levels of circulating tumor cells (CTCs) in the bloodstream of women diagnosed with metastatic breast cancer before, during, and after chemotherapy. The researchers found that women whose CTC levels went down had a much lower risk of the cancer progressing.

The researchers concluded that a drop in CTC levels meant the chemotherapy was working.

These early results look promising. Still, the study is small and the women have been followed for only 2 years. More research is needed to determine if CTC levels really are a good way to tell if chemotherapy is working, as well as if the results apply to all women and all types of breast cancer.

Stay tuned to breastcancer.org for the very latest news on treatments for metastatic and recurrent breast cancer.